APW7128 30V, 1.2MHz, White LED Driver Features General Description * Wide Input Voltage Range from 2.7V to 21V * High Current-Limit up to 3.5A * 0.5V Reference Voltage with 3% The APW7128 is the high power and high efficiency boost converter with an integrated 30V FET ideal for LCD panel backlighting applications. 30V output voltage allows for 8 high-power LEDs in series, and 3.5A inductor current limit allows for more LED strings connected in parallel. The low 0.5V feedback voltage offers higher efficiency in WLED driver applications. The wide input range from 2.7V to 21V made APW7128 a perfect solution for various applications such as LCD monitor and portable devices. The OVP pin monitors the output voltage to protect IC during open load and FB pin short circuit operations. The APW7128 provides the ALS pin to simplify the interface to an ambient light sensor for automatic dimming. The APW7128 is available in the thermally enhanced DFN-10 lead 3mm x 3mm package. System Accuracy * 50m Integrated N-FET * Fixed 1.2MHz Switching Frequency * High Efficiency up to 95% * Open-LED Protection * Under Voltage Lockout Protection * ALS Control Input Pin * Over Temperature Protection * Low Shutdown Current: <1uA * 3mm x 3mm DFN-10 Package * Lead Free and Green Devices Available Pin Configuration (RoHS Compliant) Applications * * FB 1 Display Backlighting - Automotive - LCD Monitors - Notebook Displays 10 ALS COMP 2 9 GND Metal LX Pad (Bottom) OVP 3 EN 4 PGND 5 Portable Displays 8 BP 7 VIN 6 LX APW7128 DFN3x3-10 Top View Ordering and Marking Information Package Code QA: DFN3x3-10 Operating Ambient Temperature Range I : -40 to 85 C Handling Code TR : Tape & Reel Assembly Material L : Lead Free Device G : Halogen and Lead Free Device APW7128 Assembly Material Handling Code Temperature Range Package Code APW7128 QA: APW 7128 XXXXX XXXXX - Date Code Note: ANPEC lead-free products contain molding compounds/die attach materials and 100% matte tin plate termination finish; which are fully compliant with RoHS. ANPEC lead-free products meet or exceed the lead-free requirements of IPC/JEDEC J-STD-020C for MSL classification at lead-free peak reflow temperature. ANPEC defines "Green" to mean lead-free (RoHS compliant) and halogen free (Br or Cl does not exceed 900ppm by weight in homogeneous material and total of Br and Cl does not exceed 1500ppm by weight). ANPEC reserves the right to make changes to improve reliability or manufacturability without notice, and advise customers to obtain the latest version of relevant information to verify before placing orders. Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2008 1 www.anpec.com.tw APW7128 Absolute Maximum Ratings Symbol (Note 1) Parameter VIN VIN pin to GND Rating Unit -0.3 to 30 V VLX LX pin to PGND -0.3 to 30 V VOVP OVP pin to GND -0.3 to 30 V VBP BP pin to GND -0.3 to 6 V VEN EN pin to GND -0.3 to 30 V VALS ALS pin to GND -0.3 to 6 V PGND to GND TJ -0.3 to 0.3 V 150 C -65 to 150 C 260 C Maximum Junction Temperature TSTG Storage Temperature Range TL Maximum Lead Soldering Temperature, 10 Seconds Note 1: Stresses beyond the absolute maximum rating may damage the device and exposure to absolute maximum rating conditions for extended periods may affect device reliability. Thermal Characteristics (Note 2) Symbol Parameter Package Typical Value Unit JA Junction to Ambient Thermal Resistance in Free Air DFN3x3-10 80 C/W Note 2: JA is measured with the component mounted on a high effective thermal conductivity test board in free air. The exposed pad is soldered directly on the PCB. Recommended Operating Conditions Symbol Parameter VIN VOUT Rating Unit VIN Supply Voltage, (VIN=BP) 2.7 to 5.5 V VIN Supply Voltage, (BP is open) 3.7 to 21V V up to 30 V Output Voltage TJ Operating Ambient Temperature -40 to 85 C TA Operating Junction Temperature -40 to 125 C Electrical Characteristics VIN=6V, TA = -40 to 85C, unless otherwise specified. Typical values refer to TA =25C. Symbol Parameter Test Conditions Min Typ Max Unit 2.4 2.5 2.6 V INPUT SUPPLY CURRENT AND UVLO BP Under Voltage Lockout Threshold VIN rising UVLO Hysteresis IVIN VIN Supply Current - 100 - mV EN=5V, switching - 9 15 mA EN=0V - - 1 uA - 350 - uA/V - 50 - uA 485 500 515 mV ERROR AMPLIFIER gm ICOMP VFB Error Amplifier Transconductance COMP Output Current sourcing and sinking, VCOMP=1.5V FB Voltage Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2008 2 www.anpec.com.tw APW7128 Electrical Characteristics (Cont.) VIN=6V, TA = -40 to 85C, unless otherwise specified. Typical values refer to TA =25C. Symbol Parameter Minimum FB Voltage IFB Test Conditions VALS=0.3V FB Input Bias Current FB Line Regulation VIN=2.7V to 21V Min Typ Max Unit 188 200 212 mV - - 1 A - 0.02 0.04 %/V 2.5 3.5 4.5 A INTERNAL POWER SWITCH Power Switch Current-Limit RDS(ON) Power Switch On Resistance LX Leakage Current VLX=30V - 50 100 m - - 1 A FSW Switching Frequency 0.9 1.2 1.5 MHz DMAX LX Maximum Duty Cycle 92 95 98 % 2.9 3 3.1 V/V - - 1 A Over Voltage Threshold 30 32 34 V OVP Hysteresis 2 3 4 V OVP Leakage Current - - 30 A 2.4 - - V ALS ALS Ratio VALS=1V, VALS/VFB ALS Pin Leakage VALS=5V OUTPUT OVERVOLTAGE PROTECTION CONTROL LOGIC PIN EN High-Level Input Voltage EN Low-Level Input Voltage EN Leakage Current VEN=21V - - 0.4 V - - 1 A - 150 - THERMAL SHUTDOWN Thermal Shutdown Threshold Thermal Shutdown Hysteresis Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2008 - 3 50 - C C www.anpec.com.tw APW7128 Typical Operating Characteristics VIN Supply Current vs. VIN Supply Voltage VIN Supply Current vs. VIN Supply Voltage 800 9.0 no switching VIN Supply Current (uA) VIN Supply Current (mA) 8.5 switching 7.5 6.5 5.5 4.5 700 600 500 3.5 2.5 400 0 5 10 15 20 0 25 5 10 15 20 25 VIN Supply Voltage (V) VIN Supply Voltage (V) FB Voltage vs. VIN Supply Voltage Efficiency vs. Load Current 0.510 100 95 Efficiency (%) VIN=19V FB Voltage (V) VIN=12V 90 VIN=6V 85 80 75 0.505 0.500 0.495 70 8LEDs in series 65 0.490 60 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 0 Load Current (A) 5 10 15 20 25 VIN Supply Voltage (V) FB Voltage vs. ALS Input Voltage EN Threshold Voltage vs. VIN Supply Voltage 0.55 2.0 EN Threshold Voltage (V) FB Voltage (V) 0.50 0.45 0.40 0.35 0.30 0.25 0.20 0.15 1.8 EN High Threshold 1.6 1.4 EN Low Threshold 1.2 1.0 0 0.5 1 1.5 2 2 ALS Input Voltage (V) Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2008 6 10 14 18 22 VIN Supply Voltage (V) 4 www.anpec.com.tw APW7128 Typical Operating Characteristics (Cont.) Power Switching On Resistance vs. VIN Supply Voltage Switching Frequency vs. VIN Supply Voltage 1.40 60 Switching Frequency (MHz) Power Switch On Resistance (m) 70 50 40 30 20 1.30 1.25 1.20 10 2 10 6 14 18 0 22 5 10 20 VIN Supply Voltage (V) Switching Frequency vs. Junction Temperature VIN Supply Current vs. Junction Temperature 1.50 800 1.45 750 1.35 1.30 1.25 1.20 1.15 1.10 25 no switching 700 1.40 1.05 650 600 550 500 450 400 350 300 250 1.00 200 -40 -20 0 20 40 60 -40 -20 80 100 120 140 160 Junction Temperature (oC) 0 20 40 60 80 100 120 140 160 Junction Temperature (oC) FB Voltage vs. Junction Temperature Power Switching On Resistance vs. Junction Temperature 0.510 100 0.508 0.506 80 FB Voltage (V) Power Switch On Resistance (m) 15 VIN Supply Voltage (V) VIN Supply Current (uA) Switching Frequency (MHz) 1.35 60 40 0.504 0.502 0.500 0.498 0.496 0.494 20 0.492 0.490 0 -40 -20 0 20 40 60 -40 -20 80 100 120 140 160 20 40 60 80 100 120 140 160 Junction Temperature (oC) Junction Temperature () Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2008 0 5 www.anpec.com.tw APW7128 Operating Waveforms Refer to the typical application circuit. The test condition is VIN=5V, TA= 25oC unless otherwise specified. Shutdown Start-up VEN 1 1 VEN VOUT VOUT 2 2 IIN 4 4 IIN VIN=12V, L=10uH, CCOMP=0.22uF VIN=12V, L=10uH, CCOMP=0.22uF CH1: VEN, 10V/div, DC CH2: VOUT, 10V/div, DC CH4: IIN, 500mA/div, DC TIME: 1ms/div CH1: VEN, 10V/div, DC CH2: VOUT, 10V/div, DC CH4: IIN, 500mA/div, DC TIME: 10ms/div Overvoltage Protection Switching Waveforms 1 VCOMP 1 2 VOUT 3 2 IIN 4 4 Output is open VIN=12V, L=10uF, IOUT=160mA CH1: VIN, 50mV/div, AC CH1: VCOMP, 0.5V/div, DC CH2: VOUT, 10V/div, DC CH4: IIN, 100mA/div, DC TIME: 10ms/div Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2008 CH2: VOUT, 200mV/div, AC CH3: VLX, 20V/div, DC CH4: IL, 200mA/div, DC TIME: 0.5us/div 6 www.anpec.com.tw APW7128 Pin Description PIN FUNCTION NO. NAME 1 FB 2 COMP 3 OVP 4 EN 5 PGND 6 LX Internal Power MOSFET Drain. 7 VIN Supply Voltage Input. 8 BP Output of The Internal 5V Regulator. Connect a 1F bypass capacitor to GND. Do not apply an external load to BP. 9 GND Signal Ground. 10 ALS Ambient Light Sensor Input. Allow the light sensor to control the FB voltage for LED dimming. If the ALS function is not used, tie the ALS pin to BP pin. Regulator Feedback Pin. Connect a current sense resistor to GND to set the LED current. Error Amplifier Output. Connect a 0.22F capacitor for compensation and soft-start. When EN is pulled low, an internal switch will discharge the COMP voltage to 0V. Output Over Voltage Monitor Pin. Tie to VOUT for OVP function. Enable Input Pin. Pull EN above 2.4V to enable the device; pull EN below 0.4V to disable the device. The EN pin cannot be left floating. Power Ground. Source of the internal N-channel power MOSFET. Block Diagram BP VIN OVP LDO UVLO 0.9V LX EN Control Logic Thermal Shutdown GND PGND Oscillator FB COMP 0.5V ALS Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2008 7 www.anpec.com.tw APW7128 Typical Application Circuit 6V to 21V L1 10uH D1 C1 10uF 10 7 ON 4 9 OFF 8 C2 1uF ALS VIN OVP EN COMP GND PGND BP APW7128 PWM brightness control Up to 8 LEDs per String 3 2 C3 5 0.22uF 1 FB 3V C5 1uF 6 LX Up to 8 Strings R3 120k VADJ 0V R2 24k C4 0.1uF R4 10k R1 I LED(max)=20mA 3.75 ILED(min)=0mA Figure1. Analog Dimming with PWM Voltage VDD 6V to 21V L1 10uH D1 C1 10uF 10 ALS R2 7 ON 4 9 OFF 8 C2 1uF 6 ALS LX VIN OVP EN COMP GND PGND BP APW7128 FB Up to 8 Strings C5 1uF Up to 8 LEDs per String 3 2 5 C3 0.22uF 1 R1 3.125 Figure2. Analog Dimming with External ALS Voltage Designation L1 C1 C2 C3 C5 D1 Supplier GOTREND Murata Murata Murata Murata Zowie Part Number GTSD53 GRM31CR61E106K GRM155R61A105K GRM155R60J224KE01 GRM21BR71H105KA12 MSCD104 Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2008 8 Specification 10uH, 1.33A X5R, 25V, 10uF X5R, 10V, 1uF X5R, 6.3V. 0.22uF X7R, 50V, 1uF 1.0A, 40V Wedsite www.gotrend.com.tw www.murata.com www.murata.com www.murata.com www.murata.com www.zowie.com.tw www.anpec.com.tw APW7128 Function Description Output Overvoltage Protection If the FB pin is shorted to ground or an LED fails open internal thermal sensor circuit will disable the device and allow the device to cool down. When the device's circuit, output voltage in BOOST mode can increase to potentially damaging voltages. An optional overvoltage junction temperature cools by 50C, the internal thermal sense circuit will enable the device, resulting in a pulsed protection circuit can be enabled by connection of the OVP pin to the output voltage. The device will stop output during continuous thermal protection. Thermal protection is designed to protect the IC in the event of switching if the output voltage exceeds OVP high threshold and re-start when the output voltage falls over temperature conditions. For normal operation, the junction temperature cannot exceed TJ=+125 C. below OVP low threshold. During sustained OVP fault conditions, VOUT will saw-tooth between the upper and Internal 5V LDO The APW7128 provides an internal 5V LDO for the control circuitry, and the output of the internal LDO is BP pin. lower threshold voltages at a frequency determined by the magnitude of current available to discharge the In normal operation, connect a 1F or greater capacitor to GND is recommended. The internal LDO cannot output capacitor. Note that the OVP pin must be connected to output voltage for OVP function. supply any more current than is required to operate the APW7128. Therefore, do not apply any external load to Ambient Light Sensor Interface BP pin. In applications, where the VIN is less than 5.5V, BP should be tied to VIN through a 10 resistor. The APW7128 provides the ALS pin to simplify the interface to an ambient light sensor. The ambient light sensor detects the ambient light and yields a current which is related to the illuminance. Connect a load resistor from the current output of ambient light sensor to ground to provide an output voltage to ALS pin. The ALS voltage will be divided by an internal divider circuit, and the divided ALS voltage will replace the internal reference voltage. The LED current can be calculated by the following equation: I LED = 1 V ALS x 3 R2 Note that the maximum FB voltage is set to 0.5V, and minimum FB voltage is set to 0.2V. If the divided ALS voltage is over 0.5V or less 0.2V, the LED current is limited at: ILED (MAX ) = 0 .5 V R2 ILED (MIN ) = 0 .2 V R2 where R2 is the resistor from FB to GND. Enable/Disable Pull the EN above 2V to enable the device and pull EN pin below 0.4V to disable the device. In shutdown mode, the internal control circuits are turned off, the quiescent current is below 1uA. Thermal Shutdown When the junction temperature exceeds 150C, the Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2008 9 www.anpec.com.tw APW7128 Application Information Inductor Selection Connecting more LED strings The APW7128 can drive 8 LED strings in parallel and up to 8 LEDs per string (VF<3.5V). Each string must have the A larger value of inductor will reduce the peak inductor current, resulting in smaller input ripple current, higher same number of LEDs. In the applications that have the same total number of LEDs, more strings and less LEDs efficiency and reducing stress on the internal MOSFET. However, the larger value of inductor has a large in series are more efficiency than less strings and more LEDs in series. dimension, lower saturation current, and higher series resistance. Brightness Control A good rule for determining the inductance is to allow the peak-to-peak ripple current to be approximately 30% to The method for dimming the LEDs is to apply a PWM voltage through an RC filter into the FB pin. 50% of the maximum input current. Calculate the required inductance value by the equation: The RC filter is used to convert the PWM voltage into an analog voltage. The values of the R and C depend upon L = ( V - V )x V I x F x V OUT the frequency of the PWM voltage and the amount of allowable ripple voltage on FB pin. The LED current is pro- L current. The values of R1 and R2 are calculated by the following equations: IIN = VFB x (ILED(max) x R3 + VADJ(low) - ILED(min) x R3 - VADJ(high)) VADJ(high) x ILED(max) + VFB x ILED(min) - VADJ(low) x ILED(min) - VFB x ILED(max) R1 = V FB x (1 + VOUTxILOAD VIN x It is necessary to choose an inductor that ensures the inductor saturation current rating to exceed the peak inductor current for the application. R2 R2 x V ADJ ( low ) )- R3 R3 I IN OUT IL = (30% - 50%) x IIN portional to the PWM duty cycle. 0 % duty delivers maximum LED current and 100% duty delivers minimum LED R2 = IN SW To make sure that the peak inductor current is below the current-limit 2.5A. Calculating the peak inductor current LED (max) by the following equation: where: ILED(max) is the maximum LED current ILED(min) is the minimum LED current IPEAK = IIN + 0.5 x IL VADJ(high) is the maximum PWM voltage level VADJ(min) is the minimum PWM voltage level IPEAK = VOUT x ILOAD ( VOUT - VIN) x VIN + VIN x 2 x L x FSW x VOUT where VFB is the FB pin Voltage is the efficiency Schottky Diode Selection APW7128 FB A fast recovery time and low forward voltage Schottky diode is necessary for optimum efficiency. Ensure that the 1 R2 VADJ(max) PWM Voltage diode's average and peak current rating exceed the average output current and peak inductor current. In addition, R1 R3 the diode's reverse voltage must exceed output voltage. R4 C4 VADJ(min) Figure 3. Dimming with the PWM Voltage Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2008 10 www.anpec.com.tw APW7128 Application Information (Cont.) VIN Capacitor Selection An input capacitor is required to supply the ripple current to the inductor and stabilize the input voltage. Larger L1 D1 C1 C4 LX VIN input capacitor values and lower ESR provide smaller input voltage ripple and noise. The typical value for input C3 capacitor is 2.2F to 10F. The output capacitor with typical value 1F to 10F is re- C2 COMP FB BP quired to maintain the output voltage. The COMP capacitor with typical value 0.22F to 1F stabilizes the converter and controls the soft-start. To ensure the voltage rating of input and output capaci- BOTTOM SIDE PAD GN PGN D D R2 Via connection to PGND plane tors is greater than the maximum input and output voltage. Via connection to GND plane It is recommended using the ceramic capacitors with X5R, Via connection to LX plane X7R, or better dielectrics for stable operation over the Short and wide wires entire operating temperature range. Short wires Figure 4. Layouy Guidelines Layout Consideration The correct PCB layout is important for all switching converters. If the layout is not carefully done, the regulator could show stability problems as well as EMI problems. Figure. 4 illustrates the layout guidelines; the bold lines indicate these traces that must be short and wide. The capacitors, the diode, and the inductor should be as close to the IC as possible. Keep traces short, direct, and wide. Keep the LX node away from FB and COMP pins. The trace from diode to the LEDs may be longer. The ground return of input capacitor and output capacitor should be tied close to PGND. Use the different ground planes for signal ground and power ground to minimize the effects of ground noise. Connect these ground nodes at any place close to one of the ground pins of the IC. The resistor from FB to GND should be close to the FB pin as possible. The metal plate of the bottom must be soldered to the PCB and connected to LX node and the LX plane on the backside through several thermal vias to improve heat dissipation. Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2008 11 www.anpec.com.tw APW7128 Package Information DFN3x3-10 D b E A D2 A1 A3 L E2 Pin 1 Corner e DFN3*3-10 S Y M B O L MIN. MAX. MIN. MAX. A 0.80 1.00 0.031 0.039 0.05 0.000 0.002 0.30 0.007 A1 MILLIMETERS 0.00 A3 b 0.20 REF 0.18 D D2 2.20 2.70 0.087 1.75 0.055 0.50 0.012 Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2008 0.106 0.118 BSC 0.50 BSC 0.30 0.012 0.118 BSC 3.00 BSC 1.40 e L 0.008 REF 3.00 BSC E E2 INCHES 0.069 0.016 BSC 12 0.020 www.anpec.com.tw APW7128 Carrier Tape & Reel Dimensions P0 P2 P1 A B0 W F E1 OD0 K0 A0 A OD1 B B T SECTION A-A SECTION B-B H A d T1 Application A H 178.02.00 50 MIN. DFN3x3-10 T1 C d D 12.4+2.00 13.0+0.50 1.5 MIN. -0.00 -0.20 P0 P1 P2 D0 D1 4.00.10 8.00.10 2.00.10 1.5+0.10 -0.00 1.5 MIN. W E1 20.2 MIN. 12.00.30 1.750.10 T A0 B0 F 5.50.05 K0 0.6+0.00 -0.40 3.350.20 3.350.20 1.300.20 (mm) Devices Per Unit Package Type DFN3X3-10 Unit Tape & Reel Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2008 Quantity 3000 13 www.anpec.com.tw APW7128 Reflow Condition (IR/Convection or VPR Reflow) tp TP Critical Zone TL to TP Ramp-up Temperature TL tL Tsmax Tsmin Ramp-down ts Preheat 25 t 25C to Peak Time Classification Reflow Profiles Profile Feature Average ramp-up rate (TL to TP) Preheat - Temperature Min (Tsmin) - Temperature Max (Tsmax) - Time (min to max) (ts) Time maintained above: - Temperature (TL) - Time (tL) Peak/Classification Temperature (Tp) Time within 5C of actual Peak Temperature (tp) Ramp-down Rate Time 25C to Peak Temperature Sn-Pb Eutectic Assembly Pb-Free Assembly 3C/second max. 3C/second max. 100C 150C 60-120 seconds 150C 200C 60-180 seconds 183C 60-150 seconds 217C 60-150 seconds See table 1 See table 2 10-30 seconds 20-40 seconds 6C/second max. 6C/second max. 6 minutes max. 8 minutes max. Notes: All temperatures refer to topside of the package. Measured on the body surface. Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2008 14 www.anpec.com.tw APW7128 Classification Reflow Profiles (Cont.) Table 1. SnPb Entectic Process - Package Peak Reflow Temperatures 3 3 Volume mm 350 225 +0/-5C 225 +0/-5C Volume mm <350 240 +0/-5C 225 +0/-5C Package Thickness <2.5 mm 2.5 mm Table 2. Pb-free Process - Package Classification Reflow Temperatures 3 3 3 Volume mm Volume mm Volume mm <350 350-2000 >2000 <1.6 mm 260 +0C* 260 +0C* 260 +0C* 1.6 mm - 2.5 mm 260 +0C* 250 +0C* 245 +0C* 2.5 mm 250 +0C* 245 +0C* 245 +0C* * Tolerance: The device manufacturer/supplier shall assure process compatibility up to and including the stated classification temperature (this means Peak reflow temperature +0C. For example 260C+0C) at the rated MSL level. Package Thickness Reliability Test Program Test item SOLDERABILITY HOLT PCT TST ESD Latch-Up Method MIL-STD-883D-2003 MIL-STD-883D-1005.7 JESD-22-B,A102 MIL-STD-883D-1011.9 MIL-STD-883D-3015.7 JESD 78 Description 245C, 5 SEC 1000 Hrs Bias @125C 168 Hrs, 100%RH, 121C -65C~150C, 200 Cycles VHBM > 2KV, VMM > 200V 10ms, 1tr > 100mA Customer Service Anpec Electronics Corp. Head Office : No.6, Dusing 1st Road, SBIP, Hsin-Chu, Taiwan, R.O.C. Tel : 886-3-5642000 Fax : 886-3-5642050 Taipei Branch : 2F, No. 11, Lane 218, Sec 2 Jhongsing Rd., Sindian City, Taipei County 23146, Taiwan Tel : 886-2-2910-3838 Fax : 886-2-2917-3838 Copyright ANPEC Electronics Corp. Rev. A.1 - Apr., 2008 15 www.anpec.com.tw